TRENDS IN STABILITY OF DYNAMICALLY STABLE BREAKWATERS

Joseph S. Kao, Kevin R. Hall

Abstract

The reshaping of dynamically stable breakwaters was studied subject to variations in armour stone, (gradation and shape), wave characteristics and duration of wave attack from head on waves in a two dimensional wave flume. Tests were undertaken at the Coastal Engineering Research Laboratory of Queen's University, Kingston, Canada using irregular waves. Profiles of the structure during the various stages of reshaping were measured using a semi-automatic profiler developed for this study. The volume of stones and the initial berm width required for development of a stable profile along with the extent to which the toe of the structure progressed seaward were chosen as the characteristic parameters of the reshaped breakwater. The results indicated that the toe width formed as a result of reshaping and the area of stones required for reshaping were dependent on the wave height, gradation of the armour stone and duration of the storm. The initial berm width required for reshaping was also found to be dependent on the wave height, armour stone gradation, percentage of rounded stones in the armour and the duration of the storm.